This invention pertains to methods and apparatus for carrying out high temperature chemical reactions wherein high yields of reaction product is obtained. The invention is generally directed to reductions, halogenations and chemical synthesis reactions but is not limited thereto. Exemplary reduction reactions include reduction of refractory metal compounds to the elemental metal state. Refractory metals include, by way of example and not limitation, tantalum, tungsten, molybdenum and columbium. In some instances, formation of alloys of these metals with such other metals, such as tin, etc., is possible through simultaneous reduction of the constituents. Other applications of the invention include halogenation of various oxides, for example, columbium oxide to columbium chloride. The invention also pertains to the high temperature reaction or synthesis of chemicals, for example, the synthesis of acetylene, benzine and other hydrocarbons or products which are normally carried out under high temperatures.
More particularly, the invention relates to method and apparatus for producing relatively high purity reaction products of selected characteristics involving high percentages yields and selected characteristics, all in a commercially feasible manner.
More specifically the invention is directed to the processes and apparatuses for producing reaction products, as for example, metal powders, chemicals and halogenated metals using a plasma generator for the energy required to carry out the reaction.
For example, metallic halides and oxides are reduced, metal oxides halogenated and hydrocarbons and other compounds synthesized using a plasma generator to produce reaction products of the elemental metal, metal halides or chemical compounds and are recovered in relatively pure forms and in quantities which have not ben heretofore possible by plasma processes.
The prior art of gas-discharge physics is well aware of the means for conducting chemical reactions using a plasma flow or plasma jet. The chemical reactions with which this invention is involved are similar to those of the prior art but are specially directed to reductions of metallic compounds with reductants such as, for example, hydrogen or carbon; halogenations of metal oxides and hydrocarbon synthesis. Other reactions will readily suggest themselves to those of ordinary skill in the art as the disclosure proceeds herein.
The temperatures generated in a plasma generator are relatively high and the reactions carried out thereby have heretofore been primarily of a non-commercial nature, for a variety of reasons, some of the more common being because the plasma generators could not support sustained reactions without deleterious effects, for example, plugging of the anode chamber, or could only produce laboratory quantities of desired end products, which in most instances were not of a quantity or quality needed in commercial manufacturing processes, or because the product lacked certain essential characteristics, such as, for instance, size of the reaction product where reduction to elemental metals are concerned.
Among others, the present invention provides process and apparatus for the manufacture of elemental metals of the groups IVb, Vb, and VIb of the Periodic Table wherein a compound of said metals is reacted in a high temperature reaction zone produced by a plasma generator, in a manner to produce heretofore unavailable quantities of the elemental metal of selected particle size at a satisfactory purity level, or a halogen of said metal is produced which itself may be further reacted to obtain the metal per se.
For instance, a present commercial need exists for tantalum powder of substantially pure form and having a particle size sufficiently large for the formation of electrodes for capacitors, of the dry or liquid type. The elemental metal, such as tantalum, obtained in the practice of the herein disclosed invention is of capacitor grade quality from which capacitors may be formed. In other instances, a metallic oxide may be halogenated and further reduced to the elemental method according to the practice of the invention.
According to the invention hydrocarbons such as acetylene, benzine and other compounds requiring high reaction temperatures may be synthesized.
The following examples of the practice of the invention are illustrative. In the formation of elemental tantalum, a metallic halide such as tantalum pentachloride or potassium fluotantalate is reduced in the plasma reactor utilizing a reductant such as hydrogen, in a process wherein purity of the obtained tantalum is at a high level. The particle size of the metal is selectively controlled all in a commercially sustainable and feasible process producing copious amounts of the elemental metal at high percentage yields. In the formation of a metallic halide, an oxide such as columbium oxide may be chlorinated to columbium chloride. In the synthesis of chemical compounds acetylene is synthesized from methane.